To improve the core utilization rate of pulse transformer in pulse power system, a pulse transformer reset system based on energy recovery principle is proposed. Firstly, according to the magnetic core hysteresis loop, the change process of the magnetic induction intensity of the reset system based on the energy recovery principle in one cycle is analyzed, and the solution formulas of the pulse transformer excitation current and reset capacitor voltage in different stages are deduced. A simulation model of the pulse transformer reset system based on the energy recovery principle is established, and the correctness of the theoretical analysis and solution formulasof the reset system is verified by the simulation results. On this basis, a pulse modulator test platform based on pulse transformer boosting and energy recovery reset system is constructed. The excitation currents of the pulse modulators with reset system and without reset system are compared under the same pulse width. The results show that the reset system pulse modulation can effectively improve the utilization of the magnetic core. The repetition frequency experiment is carried out on the pulse modulator with reset system, and the results show that the reset system can realize the stable operation of 1 kHz repetition frequency.